Twenty-eight extensor carpi ulnaris lesions at the wrist were treated surgically between 1990 and 2002. Fifteen patients had an isolated extensor carpi ulnaris tenosynovitis or tendinopathy, five had extensor carpi ulnaris dislocation, four had an extensor carpi ulnaris subluxation and four had an extensor carpi ulnaris rupture. Seventeen patients first developed their symptoms while playing sports. At a mean follow-up of 23 months, twenty-two patients had returned to their previous activities. Seven of the 27 patients had lost more than 30% of their grip strength and five had restricted wrist motion. Two needed an extensor carpi ulnaris tenolysis. Pure isolated extensor carpi ulnaris lesions are rare and associated ulnar sided lesions (eleven triangular fibrocartilage complex tears and four lunotriquetral ligament tears), as well as possible predisposing factors (seven anomalous tendon slips, four ulnar styloid non-unions and one flat extensor carpi ulnaris tendon groove), were frequent. A classification of extensor carpi ulnaris tendon and subsheath lesions was developed to allow the surgeon to adequately evaluate the different components of these lesions.